From: houlong wei <houlong.wei@mediatek.com>
To: <Irui.wang@mediatek.com>,
Dafna Hirschfeld <dafna.hirschfeld@collabora.com>,
Alexandre Courbot <acourbot@chromium.org>,
Hans Verkuil <hverkuil@xs4all.nl>
Cc: "Linux Media Mailing List" <linux-media@vger.kernel.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
"kernel@collabora.com" <kernel@collabora.com>,
"Enric Balletbo i Serra" <enric.balletbo@collabora.com>,
"Dafna Hirschfeld" <dafna3@gmail.com>,
"Tiffany Lin (林慧珊)" <tiffany.lin@mediatek.com>,
"Andrew-CT Chen (陳智迪)" <Andrew-CT.Chen@mediatek.com>,
"Minghsiu Tsai (蔡明修)" <Minghsiu.Tsai@mediatek.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Matthias Brugger" <matthias.bgg@gmail.com>,
houlong.wei@mediatek.com
Subject: Re: [PATCH v4] media: mtk-vpu: Ensure alignment of 8 for DTCM buffer
Date: Wed, 3 Nov 2021 16:03:28 +0800 [thread overview]
Message-ID: <c01c2c6e2351c915fb6e55b025bf2ab5c449f045.camel@mediatek.com> (raw)
In-Reply-To: <9475ac5b-79fe-da0e-ed1c-a91275cad46e@collabora.com>
Add mtk-vpu driver expert irui.wang in the loop.
On Mon, 2021-10-18 at 15:07 +0800, Dafna Hirschfeld wrote:
>
> On 18.10.21 03:16, Alexandre Courbot wrote:
> > Hi Hans!
> >
> > On Mon, Oct 4, 2021 at 6:37 PM Hans Verkuil <hverkuil@xs4all.nl>
> > wrote:
> > >
> > > On 20/09/2021 19:04, Dafna Hirschfeld wrote:
> > > > From: Alexandre Courbot <acourbot@chromium.org>
> > > >
> > > > When running memcpy_toio:
> > > > memcpy_toio(send_obj->share_buf, buf, len);
> > > > it was found that errors appear if len is not a multiple of 8:
> > > >
> > > > [58.350841] mtk-mdp 14001000.rdma: processing failed: -22
> > >
> > > Why do errors appear? Is that due to a HW bug? Some other reason?
> >
> > MTK folks would be the best placed to answer this, but since the
> > failure is reported by the firmware I'd suspect either a firmware
> > or
> > hardware limitation.
> >
> > >
> > > >
> > > > This patch ensures the copy of a multiple of 8 size by calling
> > > > round_up(len, 8) when copying
> > > >
> > > > Fixes: e6599adfad30 ("media: mtk-vpu: avoid unaligned access to
> > > > DTCM buffer.")
> > > > Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
> > > > Signed-off-by: Enric Balletbo i Serra <
> > > > enric.balletbo@collabora.com>
> > > > Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com
> > > > >
> > > > Reviewed-by: Houlong Wei <houlong.wei@mediatek.com>
> > > > ---
> > > > changes since v3:
> > > > 1. multile -> multiple
> > > > 2. add inline doc
> > > >
> > > > changes since v2:
> > > > 1. do the extra copy only if len is not multiple of 8
> > > >
> > > > changes since v1:
> > > > 1. change sign-off-by tags
> > > > 2. change values to memset
> > > >
> > > > drivers/media/platform/mtk-vpu/mtk_vpu.c | 15 ++++++++++++++-
> > > > 1 file changed, 14 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/media/platform/mtk-vpu/mtk_vpu.c
> > > > b/drivers/media/platform/mtk-vpu/mtk_vpu.c
> > > > index ec290dde59cf..1df031716c8f 100644
> > > > --- a/drivers/media/platform/mtk-vpu/mtk_vpu.c
> > > > +++ b/drivers/media/platform/mtk-vpu/mtk_vpu.c
> > > > @@ -349,7 +349,20 @@ int vpu_ipi_send(struct platform_device
> > > > *pdev,
> > > > }
> > > > } while (vpu_cfg_readl(vpu, HOST_TO_VPU));
> > > >
> > > > - memcpy_toio(send_obj->share_buf, buf, len);
> > > > + /*
> > > > + * when copying data to the vpu hardware, the memcpy_toio
> > > > operation must copy
> > > > + * a multiple of 8. Otherwise the processing fails
> > >
> > > Same here: it needs to explain why the processing fails.
>
> Is writing 'due to hardware or firmware limitation' enough?
> If not, then we should wait for mediatek people's response to explain
> if they know more
>
> > >
> > > > + */
> > > > + if (len % 8 != 0) {
> > > > + unsigned char data[SHARE_BUF_SIZE];
> > >
> > > Wouldn't it be more robust if you say:
> > >
> > > unsigned char data[sizeof(send_obj->share_buf)];
> >
> > Definitely yes.
>
> I'll send v5 fixing this
>
> >
> > >
> > > I also think that the SHARE_BUF_SIZE define needs a comment
> > > stating that it must be a
> > > multiple of 8, otherwise unexpected things can happen.
> > >
> > > You also noticed that the current SHARE_BUF_SIZE define is too
> > > low, but I saw
> > > no patch correcting this. Shouldn't that be fixed as well?
> >
> > AFAICT the firmware expects this exact size on its end, so I don't
> > believe it can be changed that easily. But maybe someone from MTK
> > can
> > prove me wrong.
> >
>
> I looked further and noted that the structs that are larger than
> 'SHARE_BUF_SIZE'
> (venc_ap_ipi_msg_enc_ext venc_ap_ipi_msg_set_param_ext)
> are used by drivers that don't use this vpu api, so actually
> SHARE_BUF_SIZE is
> not too low and as Corurbot worte probably not changeable.
>
>
> Thanks,
> Dafna
>
> > Cheers,
> > Alex.
> >
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next prev parent reply other threads:[~2021-11-03 8:11 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 17:04 [PATCH v4] media: mtk-vpu: Ensure alignment of 8 for DTCM buffer Dafna Hirschfeld
2021-10-04 9:37 ` Hans Verkuil
2021-10-18 1:16 ` Alexandre Courbot
2021-10-18 7:07 ` Dafna Hirschfeld
2021-11-03 8:03 ` houlong wei [this message]
2021-11-03 9:19 ` Irui Wang
2021-11-03 11:04 ` Dafna Hirschfeld
2021-11-09 8:46 ` Dafna Hirschfeld
2021-11-10 3:11 ` Irui Wang
2021-11-29 8:11 ` Dafna Hirschfeld
2021-11-29 14:39 ` Dafna Hirschfeld
2021-12-06 7:23 ` Alexandre Courbot
2022-02-15 9:41 ` AngeloGioacchino Del Regno
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